1. Field of the Invention
The present invention relates generally to a document scanning system and in particular to scanning and capturing digital images using residue detection.
2. Description of the Related Art
Scanners are an important part of a word processing and/or personal computer environment. A scanner is a device that optically scans printed or handwritten paper documents, objects, and photographs and creates digital images. One example of a scanner is a desktop or flatbed scanner that comprises a glass window on which a document is placed. A light positioned under the glass window is moved across the document to capture a digital image of the document and store the image in memory. With the digital image in memory, the image may be displayed, copied, transferred, printed, or altered as desired.
Scanning software, called a driver, is utilized to capture an image of a document. TWAIN is a common software language that scanner manufacturers use to communicate with scanners. The TWAIN driver acts as an interpreter between any application that supports the TWAIN standard and the scanner. The user configures the controls provided by the TWAIN driver to specify the scanning mode (e.g., color or black and white), the scanning resolution (e.g., 100 dpi or 200 dpi), the area on the flatbed glass window to be scanned, and other scanning characteristics, such as desired tonal quality and color balance of the scanned image. Once a document that has been placed on the glass window has been scanned, the TWAIN driver transfers the scanned image into memory.
After the images are stored in memory, a user may need to edit a scanned image because the image contains unwanted or irrelevant detail. A user may edit the scanned image using a graphics editing software product such as Adobe® Photoshop®. The graphics editing software enables a user to remove unwanted detail by cropping the image. Cropping refers to removing unnecessary or unwanted portions of the image, thereby improving the overall composition of the document.